On April 3, the National Reconnaissance Office successfully launched a classified intelligence satellite into orbit from Vandenberg Air Force Base. Notwithstanding the usual operations security measures, amateur satellite trackers were able to locate the satellite in orbit within a few hours and even to videotape its passage overhead.

Last week's launch is the first of four scheduled launches of NRO satellites in the next five months. Last year, the NRO launched six satellites over a seven month period.

"We are in the middle of a launch campaign with an unprecedented operational tempo across national security space programs," said Gil Klinger, deputy assistant secretary of defense for space policy, at a March 8 hearing of the House Armed Services Committee.

"Many of our space capabilities have become the 'dial tone' of national security," Mr. Klinger said. "And like the dial tone of our telephones, we take their availability and presence for granted, noticing only when there is an unplanned service interruption."